January 8th, 2013

By 

“Cassandra is critical for being able to look up historical behavior data quickly, so that we can do these model updates with low latency.”

-Thomas Pinckney, Sr. Director of Engineering at eBay

Thomas Pinckney Sr. Director of Engineering at eBay

What does eBay/Hunch do?

We’re building a next generation recommendation system at eBay. By understanding each person’s unique tastes, we can help people find what they’re looking for faster or even help them discover things they’ll love that they didn’t even know about.

 

How are you using Apache Cassandra?

We are storing user activity data on Cassandra, representing it as a graph that is made up of edges between users and items that the user has indicated an interest or disinterest towards . As new behavioral data is recorded, in real time, we update our models about what the user is predicted to like or not. Cassandra is critical for being able to look up historical behavior data quickly, so that we can do these model updates with low latency.

 

What made you choose Cassandra?

It was well suited to store graph structures (using wide-rows) and it scaled better than the alternatives we evaluated.

 

What tips do you have for someone getting started with Cassandra?

Someone new to Cassandra should understand that it’s different than any relational database and it requires very different query and update patterns.  They should also be careful about disk space. When on STCS, it’s very important to keep up to 50% of disk space free to give compactions enough space to   finish. 

 

Are you running Cassandra in the cloud or your own DC?

Multiple of our own data centers.

 

Anything else that you’d like to add?

Thanks for helping make an awesome product!

 

To view the full DataStax case study visit,

http://www.datastax.com/wp-content/uploads/2012/12/DataStax-CS-eBay.pdf 

 

LinkedIn